Soft tissue augmentation for cosmetic purposes and to repair congenital or trauma-caused defects is a growing technique in the medical profession. Solid or liquid silicone implants have been used for some years, and more recently, a collagen preparation ("Zyderm") that is specifically described in Daniels et al., U.S. Pat. No. 3,949,073, has been used in cosmetic facial repair to remove wrinkles, etc. The silicone implants have never been entirely satisfactory because they tend to harden or calcify, and the collagen preparation elicits an inflammatory immune response in a small but significant number of patients. The collagen treatment is usually not permanent, so it must often be repeated periodically, e.g., every 12 to 24 months. An inflammatory immune response is sometimes elicited with collagen upon retreatment, even if it was absent in earlier treatments. [Ref., Webster et al., Arch. Otolaryngol., 110, 656(1984), Cohen et al., Plast. Reconst. Surg., 73(5), 857(1984), and Aran et al., Plast. Reconst. Surg., 71(5), 731(1983).]
The present invention is based on the discovery that crosslinked polyvinyl pyrrolidone ("PVP") can be used to augment soft tissue in mammals, including humans, to treat defects therein, with a remarkable lack of tissue reaction. The treatment is long-lasting, if not permanent, so the need to re-treat as one must do in most cases with collagen, is much reduced if not eliminated entirely.